The occurrence of osteonecrosis following renal transplantation is well recognised but its pathogenesis remains unknown. We have quantified the number of empty osteocytic lacunae in the subchondral bone of femoral heads from a control group of patients, and compared these with femoral heads from a group of renal transplant recipients without evidence of overt osteonecrosis. There is a significant increase in empty osteocytic lacunae in renal transplant patients. We conclude that loss of osteocytes precedes other manifestations of osteonecrosis.

The clinical and pathological findings in a case of early avascular necrosis of the femoral head following renal transplantation are described. Regions of subchondral bone distant from the principal lesions showed increased numbers of empty osteocytic lacunae. This has been quantified and it is suggested that a loss of osteocytes is perhaps one of the earliest lesions leading to established avascular necrosis.